A known inkjet printing apparatus comprises a supplying conveyor, a receiving conveyor and a sheet guidance unit for guiding a sheet from the supplying conveyor to the receiving conveyor. The supplying conveyor, such as a print belt conveyor having a transport belt for advancing the sheet along an inkjet print station, is arranged for advancing the sheet in a transport direction towards the receiving conveyor. Said print station is arranged for applying an inkjet image onto a process side of the sheet using an ink, such as by applying dots of an aqueous ink.
The supplying conveyor may have a suction mechanism arranged for providing a suction force to attract a contact side of the sheet towards the transport belt, the contact side being opposite to the process side. As such, a force is provided for driving the sheet in the transport direction towards the receiving conveyor along with a movement of the transport belt of the supplying conveyor in the transport direction.
The receiving conveyor comprises a transport belt for transporting the sheet having a support surface for supporting the sheet in contact with the contact side of the sheet while transporting the sheet. The receiving conveyor may further comprise a suction mechanism arranged for providing a suction force to attract the contact side of the sheet towards the support surface of the transport belt of the receiving conveyor.
The sheet guidance element is arranged downstream of the supplying conveyor in the transport direction for guiding the sheet towards the receiving conveyor. The sheet guidance element comprises a guidance surface for supporting the sheet in contact with the contact side of the sheet and guiding the sheet along the sheet guidance element towards the receiving conveyor.
The guidance surface of the sheet guidance element is arranged partly over the transport belt of the receiving conveyor. Behind an end of the guidance surface in the transport direction the sheet is allowed to land on the support surface of the transport belt of the receiving conveyor.
When the printing station forms an inkjet image on the process side of the sheet by applying dots of an aqueous ink, the printed sheet becomes wet due to the aqueous ink dots. The moisture is absorbed into the sheet and enlarges the fibers of the sheet at the process side of the sheet depending on the sheet properties. As a result, the sheet may become curled at the side edges and/or the corners of the sheet.
Additionally, environmental conditions, such as a humidity of the air, may affect curling of the sheet. Said curled sheet, when leaving the sheet guidance unit, lands on the transport belt of the receiving conveyor in an undetermined way. As a result, after landing of the sheet on the support surface of the receiving conveyor and attracting the sheet to the support surface, wrinkling may occur in the sheet. These wrinkles may even become fixed in the sheet during a drying step of the printed sheet in a drying unit arranged downstream of the sheet guidance unit. As a result, the sheet may be permanently deformed by said wrinkles.